This invention relates to gas compressors and more particularly to a capacity control system for a rotary gas compressor.
Rotary gas compressors of the vane type comprise an eccentric rotor containing a plurality of radially extending blades engaging a cylindrical housing. The eccentric rotor is in substantial contact with the cylindrical housing over a minor portion of the housing and is spaced from the housing over a substantial portion of the housing periphery to form a crescent-shaped working chamber. The chamber is provided with one or more suction or inlet ports on one side of the contact area and one or more discharge or outlet ports on the other side of said contact area. As the rotor is rotated within the housing, the radially extending blades contact the housing periphery and compress the gas entering the suction or inlet port throughout the crescent-shaped working chamber and the compressed gas is discharged through the discharge or outlet port.
It is sometimes desirable to control the capacity of such a rotary gas compressor. One such control is shown in U.S. Pat. No. 3,799,707 wherein a rotatable control plate containing an elongated arcuate aperture is positioned against the end of the bladed rotor and a plurality of slots are provided in the periphery of the rotor so that when the control plate is rotated the elongated arcuate aperture can be placed in communication with the rotor slots to thereby vent the compression side of the working chamber to the suction or inlet side of the chamber to control the capacity of the compressor.